1. Field of the Invention
The present invention relates to the field of integrated circuits. More specifically, the present invention relates to data transfer between an SOC core and devices external to that core.
2. Background Information
Advances in integrated circuit technology have led to the birth and proliferation of a wide variety of integrated circuits, including but not limited to application specific integrated circuits, micro-controllers, digital signal processors, general purpose microprocessors, and network processors. Recent advances have also led to the birth of what's known as “system on a chip” or SOC. Typically, an SOC includes multiple “tightly coupled” subsystems performing very different functions.
These SOC designs frequently include a “core design” (“core”) to which adopters will add additional features as necessary. Examples of the additional features include “external” memory devices such as flash memory, communications interface devices such as Ethernet controllers and other “intellectual property” or IP components. When this occurs, any number of the subsystems of “core” may have a need to communicate with devices that are “external” to the “core”.
Frequently these “external” devices have been designed to interface to a popular processing device or a standard bus interface. Such devices including processors from Intel® Corporation and processors from Motorola® Corporation. Such bus interfaces include PCI, PCMCIA, and CardBus. To maximize the flexibility to the designers of the system containing the SOC design, the ability of the SOC design to flexibly and/or efficiently support multiple types of “external” devices is desirable.
Accordingly, a more flexible and/or efficient mode of communicating with devices which are not part of the core integrated circuit design is desired.